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    Tissue Engineering

    (K-428) Antibacterial Silk Fibroin Based Biofabrics with Controlled Release

    Thursday, October 12, 2023
    9:30 AM – 10:30 AM PDT
    Location: Exhibit Hall - Row K - Poster # 428

      Presenting Author(s)

    • GN

      Grace B. Neven

      Student
      South Dakota School of Mines and Technology
      Monument, Colorado, United States

      • Co-Author(s)

    • JH

      Jordan Hoops

      PhD Candidate
      South Dakota School of Mines and Technology, United States

    • TW

      Travis Walker

      Associate Professor
      South Dakota School of Mines and Technology, United States

    • Tugba Ozdemir

      Assistant Professor
      South Dakota School of Mines and Technology, United States

    Introduction:: Introduction:
    Pathological biofilm formation is a major issue that restricts the functional use of implants and scaffolds. Embedding nanoparticles into implants have been a viable strategy however it significantly compromise the mechanical properties of the implants as it destructs the bulk material structure. Introducing antibacterial compounds woven in biofabrics is a novel strategy to retain antibacterial activity without compromising mechanical properties. Here we propose to develop a controlled release antibacterial biofabric utilizing silk fibroin (SF) and cationic hyperbranched polyethyleneimine (PEI) using a bottom-up materials development strategy to strategically incorporate these two polymers. We hypothesize the SF-PEI biofabric will have the greatest mechanical properties and the longest antimicrobial effect.  We summarized our study design in Figure 1.

    Materials and Methods::

    Silk Extraction  Regenerated SF was produced following the methods reported earlier (Ugur’paper).


                Microparticle Preparation and Characterization  Briefly, 4% w/v silk solution was added dropwise to pure acetone solution and was sonicated and sonicated for 30 minutes with a 50% amplitude with 30 second pulses.  Afterwards, the solution was left out overnight in the fume hood and stirred. The remaining dried particles were then crushed with a mortar and pestle and set aside. SF-PEI particles were prepared similarly only with addition of PEI in acetone solution during particle preparations


                Electrospinning Silk fibroin was combined with different concentrations of PEI and electrospinning was performed following the conditions summarized in Table 1.


                Antibacterial Test: Pseudomonas Aeruginosa (ATC 39327) was used to study the antibacterial effects of SF and PEI particles. The bacterial solution was diluted to 0.5 CFU (OD600 nm) before seeding. Briefly SF only and SF/PEI particles and nanofibers will be “sandwiched” between 2 ml of nutrient agar.  This will be done by allowing the first 1 ml of agar to solidify before adding particles after 10-15 minutes, and then adding the second 1 ml.  The solution was allowed to solidify before bacterial solution was thinly spread. 


                Mechanical Testing: Based on antibacterial activity, the experimental nanofibril material discs will be reproduced and analyzed by Dynamic Mechanical analysis to understand the difference between the particles embedded verse the nanofibers embedded in agar.  



    Results, Conclusions, and Discussions::

    Results:


    Dynamic light scattering (DLS) analysis was performed using a Malvern NanoZS zetasizer and based on the initial experiments the particle size was reported to be 598.7 nm with a poly dispersity index of 0.407 as shown in Fig 2.  Separately, polyblend electrospinning was performed to produce nanofibers.  Table 1 details the conditions which were optimized to achieve the mats shown in Figure 3. The mats are intact and nanofiber structures were confirmed with Scanning electron microscopy (SEM) (SF nanofiobers only) with thin coating. Ongoing experiments are focusing on increasing the mat size and characterizing the morphological properties of the membranes. Furthermore, coaxial electrospinning will be performed to increase sustainability of PEI based antibacterial effect.


    Discussion   


    In this study we would like to achieve antibacterial biofabrics based on SF and PEI to be utilized in implants as a reinforcing and antibacterial agent. Core-shell nanofibers proposed in this study are expected to prolong the antibacterial effect.



    Acknowledgements (Optional): :

    References (Optional): :

    References


    Karatepe, U. Y., & Ozdemir, T. (2020, April 15). Improving mechanical and antibacterial properties of PMMA via polyblend electrospinning with silk fibroin and polyethyleneimine towards dental applications. Bioactive Materials. https://www.sciencedirect.com/science/article/pii/S2452199X20300578